# Questions tagged [everyday-life]

Concerns the application of the laws of physics to analyze common situations encountered in everyday life.

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### Why are swimmers slower in shallow pools?

When I heard that swimming pools in the Olympics were slow due to shallowness ($\approx 2 \,\text{m}$ instead of $3 \,\text{m}$ deep), I thought it was due to the no-slipping condition, as for example ...
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### How does one start swinging on a swing/hammock? [duplicate]

Let's say Alice is sitting on a swing/hammock, in its rest position. In order to start swinging, she moves her body in the way everyone knows how to do, to start swinging. From a conservation of ...
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### Why does the pet's water bowl overflow?

So when i give the pet fresh water in a stainless steel bowl that i place on a mat according to the attached picture, from $t=0$ the bowl is at rest, the water normally oscillates in the bowl like a ...
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### How exactly does a seashell make the humming sound?

My little brother asked me where the ocean-like sounds came from inside of a sea shell. I told him that the air trapped inside the shell vibrates, making a sound. But then he asked me why the air had ...
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### How does a vehicle's brake affect the friction between the vehicle and ground?

When brakes are activated in a vehicle it decelerates. Analysing its motion, there can be only one force that can be responsible for it: the friction between the car and the ground. So does braking ...
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### Motion of bowling ball

I'd like to model the motion of an asymmetric bowling ball thrown on a bowling lane. I know there's forward momentum and angular momentum that moment the ball is released, and there's of course ...
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### Why do most fish wiggle their tails side to side, and not up-down?

Is moving a vertical fin side to side more efficient than moving a horizontal fin up and down in water for fish locomotion? The answer might lie in how fish propel themselves using vortices, but I don'...
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### Why does my curry "bounce back" after stirring?

I recently cooked a big pot of curry, consisting largely of coconut milk, a bit of chicken stock and some vegetables. You can probably imagine that it was somewhat thick in consistency. The cooking ...
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### Why do gaps in my blinds create multiple lines?

Multiple lines appear on my floor every morning from the gaps in my blinds. Why does this happen and does it have to do with light being a wave, like in the double slit experiment? If so could it be ...
378 views

### Should I hold a baby formula bottle to cool it down faster?

This is an interesting and somewhat surprising physics problem - holding a hot object in your hand will cool it down faster, even if the air around is colder. I guess that 90% of people would be ...
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### How is energy converted when matter is deformed?

This question pertains to a project we are doing in class. In the project, we are discussing the various forces governing certain sports. I chose basketball, and one of the main things to write about ...
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### Why clothes keep us warm?

I want to understand why clothes keep us warm. I understand that they reflect back thermal radiation and also trap air thus significantly reducing cooling due to thermal convection. My question is, do ...
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### The physics of swimming

How does the straight leg flutter kick provide propulsion for a swimmer? The mechanical symmetry seems to preclude generation of a net force.
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### Is it possible to see thermal columns?

The most common way gliders gain altitude is to circle in a thermal. Thermals are often found below cumulus clouds, or above dark areas on the ground. Without these signs, they are harder to find and ...
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### Rotating a Pot of Boiling Water on a Stove

I have just boiled a half dozen eggs and wanted to ask about a phenomenon I have witnessed for years but have bottled up inside for so long. Why, when the water is near boiling and nice and hot, does ...
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### Why do large trucks have a longer stopping distance than cars?

It's common knowledge that large, heavy trucks can't brake as sharply as small cars. According to the Federal Motor Carrier Safety Administration: The average stopping distance for a loaded tractor-...
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### Does a rubber mat reduce the impact to the floor below?

My lack of physics knowledge is preventing me from solving an everyday life problem. Please bear with me! Say I have a second-floor apartment and I want to do deadlifts. I am afraid of the floor ...
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### How does the mirror know what’s behind the paper?

I found this on social media. Although it was posted for fun, this is a valid question: How does the mirror know what’s behind the paper? Show me how light reflected from the egg reaches the mirror.
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### Why do jet engine vortices go toward the ground?

This image was shown to us to illustrate how a tornado forms due to a low pressure region (also see Jet engine vortices). I find it odd that the tornado always ends up at the ground, where it is a ...
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### Doubt in pitch of screw gauge [closed]

I have just started learning about screw gauge and I came across this statement about pitch The pitch is the distance between two consecutive threads of a screw which is equal to the distance moved ...
1 vote
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### Black car or white car? Let's solve this one for all

I ask this question because I do not think that in Temperature behavior over time of black or white cars in hot, sunny regions it was properly resolved. One answer is about doing calculations with ...
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### Would placing sand bags over the top of a car's strut housing reduce the jarring impact felt when the car hits a pothole? [closed]

I live in an urban area where many of the streets have pot holes and some of these streets have some very large and deep potholes. I have been wondering lately if it would be worth the effort to try ...
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### How to dry a cup?

If you wash a cup and shake it out thoroughly so there are no longer any drops of water large enough to move, it seems like the cup ought to dry faster by putting it right side up, since all drying ...
389 views

### Why doesn't the liquid in a liquid-in-glass thermometer slide down when you turn it upside-down?

This question applies to both mercury and alcohol thermometers. I assume the answers would be similar, but maybe not. My understanding is that the capillary in a liquid-in-glass thermometer consists ...
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### General Doubt. My doubt about combustion

When we give flame to a newspaper it burns readily. What we need for a fire (fuel, heat, Oxygen) is also known as the fire triangle. But why does the paper not burn when we pour boiling water over it? ...
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### Why does microwave take more time to heat more food?

As I understand, a microwave works by generating an electromagnetic field. As food enters this field, waves will transfer energy to those food particles that are intercepted by waves, and those ...
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### What is the difference between heating and cooling, fundamentally?

Context: My physics friend told me that heating and cooling effects are identical if you flip the vertical coordinates accordingly. If you heat a room from below, the warm air rises. Identically, air ...
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### Bicycle Uphill vs. Walking Uphill

When bicycling uphill, I have noticed it takes a enormous amount of effort compared to just walking uphill. However, when on level ground, bicycling seems to take considerably less effort than walking....
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### Can cell phones send message in the elevator?

From Gauss's theorem, a closed, hollow conductor shields its interior from fields due to charges outside, but does not shield its exterior from the fields due to charges placed inside it. So my ...
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### Why are water bubbles created at the top of the bottle if the water level is higher?

Water bubbles created at the top of the bottle if the water level is higher: but water bubbles is not created at the top of the bottle if the water level is lower: This question is very different ...
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### Why is it so much easier to kick a basketball when it is just bouncing back from the ground?

A basketball coach showed me that when you bounce a basketball back from the ground, it is much easier to kick it far away (actually it shoots out like a rocket), but when you want to kick it like a ...
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### How does the distribution of floor choices of your co-passengers affect your time of arrival in an elevator?

Note: This is a wiki post. Suppose you are late for a meeting and you have to take an elevator. The floor choice of your fellow passengers influences how late you will reach your destination. If ...
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### Why are we able to observe seemingly "inertial objects" in our day to day life? (apparent paradox from Newton's second law)

On the table and near to the computer where I write this question on, is my phone, and in my observation, it is completely still. Now, by Newton´s first law, since it is inertial, there is no net ...
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### How does a seatbelt help in a car crash? [closed]

If you are in a car crash, you will likely have on a seatbelt because they are supposed to help you from getting injured/harmed. But, I don't think they are that much of a help. First of all, say you ...
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### When a bus goes around a corner, does the person sitting at the back travel further distance than the person sitting at the front?

This is a bit of childish question. When a bus goes around a corner, does the person sitting at the back travel further distance than the person sitting at the front? My thought is no because the bus ...
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### Does glass slowly (invisibly) degrade until it breaks?

(This question is about non-tempered glass.) I broke my favorite glass (tumbler) today, dropping it in my (ceramic) sink while trying to refill it. :( I'm kind of a klutz - that's far from the first ...
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### Can I get burned with warm air?

If temperature is the "average" result of measuring a mix of hot and cold air particles, then I can be in a room of some warm temperature but being hit with both extremely hot particles and ...
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### Does the fingernail test for detecting two-way mirrors really work?

I was looking for the working of a two way mirror when I came across this video. The person says that if you place your finger on the mirror and there's no gap between the image and the finger, then ...
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### How does a Magic Mirror work?

I recently found out about the Magic Mirror. Both sides of the mirror look the same, and it appears to be dark, if looked at closely, like sunglasses (but lighter in colour) but looks like a normal ...
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### Would a giant ball on earth roll towards the poles?

The radius of the earth is higher at the equator than at the pole. Would it mean then, that if I put a giant ball at the equator, it would roll up towards the pole? Why, why not?
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### Microwave oven efficiency and conservation of energy

Wikipedia says that microwave ovens can be around 50-64% efficient at converting electricity into microwaves. Where does the energy lost at this stage go? And how much of the energy that is ...
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### On a tinted (reflective) window, why do I need to look from up close to see inside?

I've noticed that on a really tinted window, when looking from farther (and even pretty close just not touching the window), you cannot look inside, but when you put your head so close to the window, ...
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### Physics of paintings created by the orbit of swinging buckets filled with paint

I am intrigued about the physics behind these paintings, which are created by swinging a bucket with a hole filled with paint from a rope (here it is another example). In principle, it seems to be a ...
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### Ultrasonic whistling

My friend from physics who doesn't know whistling says he is good at whistling, but the resonant frequencies are ultrasonic so others cannot hear it. Could this be right, or is he just bluffing? ...
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### Why does the defroster make the windshield even more foggy at first?

I have noticed that sometimes when I use the defroster, at first the windshield becomes even more foggy, almost impossible to see through. Then, after a while the defroster starts having effect and ...
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### Why cookies don't soak linearly in function of temperature?

I like to soak cookies in large coffee mug for breakfast. As a direct result of this, sometimes I try to soak the cookie in too quickly. The whole story is this: When I try to soak the cookie in and ...
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### Why does water warm gradually when a faucet is opened?

When you turn on a hot water tap after some idle period, you first get the cooler water that's been in the pipe, then gradually it warms up to the tank temperature. I've wondered why the warmup is ...
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### When doing Ice Skating, is it more painful to fall in motion or without motion?

Let's imagine I'm ice skating on a perfectly flat surface. In the first scenario, I am falling motionless. I expect my forces to looks like this: In the second scenario, I am falling with some speed, ...